Apparatus for setting fluid level in an automatic transmission

ABSTRACT

An apparatus for setting a level of fluid in an oil reservoir of an automatic transmission comprises a standpipe attached to the oil reservoir, and a regulator movable relative to the standpipe. Alternative means move the regulator relative to the standpipe to set a height of the regulator.

TECHNICAL FIELD OF THE INVENTION

[0001] This invention relates generally to transmissions for motor vehicles, and relates more particularly to a standpipe for setting the fluid level of an automatic transmission.

BACKGROUND OF THE INVENTION

[0002] Motor vehicles generally require a power plant such as an internal combustion engine, a power train and wheels. The internal combustion engine produces force by the conversion of the chemical energy in a liquid fuel into the mechanical energy of motion (kinetic energy), and the power train transmits this resultant force to the wheels to provide movement of the vehicle. The main component of the power train is typically referred to as the transmission. Engine torque and speed are converted in the transmission and delivered to the driven wheels in accordance with the vehicle's tractive-power availability. The vehicle's transmission is also capable of controlling the direction of rotation being applied to the wheels, so that the vehicle may be driven both forward and backward.

[0003] Automatic transmission architecture and fluid characteristics most often result in an aggressive rise in fluid level with increasing temperature over the transmission operating range. As a result, it is often advantageous to the proper operation of an automatic transmission that the fluid level is set accurately as a function of temperature.

[0004] Fluid filling devices and methods have been proposed to fill transmissions with an operating fluid. U.S. Pat. No. 5,456,295 shows a transmission oil fill tube in which a sealed adapter is employed at the upper end to effect filling of a transmission sump with oil to a desired level. An air pressure device is used to sense changes in the fluid level of the transmission fluid until a predetermined level is reached. U.S. Pat. No. 5,860,459 teaches a top off fill wand assembly for adding and removing operating fluid from an automatic transmission. If the fluid level is low, the fill wand delivers fluid to a sump, and if the level is high, the wand removes fluid. In U.S. Pat. No. 4,877,066, an optical sensor and associated amplifier are employed to sense the distance of the surface of the fluid from the end of a fluid dispensing device and to signal a controller to operate a fluid dispenser to effect the supply of fluid until a predetermined fluid level is obtained. Each of these patents is hereby incorporated by reference.

SUMMARY OF THE INVENTION

[0005] The present invention is an apparatus for setting a level of fluid in an oil reservoir of an automatic transmission. The apparatus comprises a standpipe attached to the oil reservoir, and a regulator movable relative to the standpipe. Alternative means move the regulator relative to the standpipe to set a height of the regulator.

[0006] Accordingly, it is an object of the present invention to provide an apparatus of the type described above that sets the fluid level in an automatic transmission of a motor vehicle.

[0007] Another object of the present invention is to provide an apparatus of the type described above that regulates the fluid level in an automatic transmission as a function of the fluid temperature.

[0008] Another object of the present invention is to provide an apparatus of the type described above that accurately sets the fluid level in an automatic transmission as a function of the temperature of the fluid in the transmission or vehicle assembly plant without the need for high cost tooling. In this environment, the top off process is performed by removing the center plug from the standpipe and introducing additional fluid to the transmission via a fill hole in the case. The regulator of the standpipe allows the fluid overage to flow into the center of the standpipe out of the transmission reservoir. Once the presence of fluid is detected the fill equipment terminates the addition of fluid. The fluid level is thus precisely set for the given fluid temperature. The center plug and fill hole plug are installed and the process is complete.

[0009] Another object of the present invention is to provide an apparatus of the type described above whereby the accurate setting of fluid level in an automatic transmission as a function of the temperature of the fluid is readily accomplished at either the service center or by the end user of the product using similar methods as the assembly plant.

[0010] These and other features and advantages of the invention will become further apparent from the following detailed description of the presently preferred embodiments, read in conjunction with the accompanying drawings. The detailed description and drawings are merely illustrative of the invention rather than limiting, the scope of the invention being defined by the appended claims and equivalents thereof.

BRIEF DESCRIPTION OF THE DRAWINGS

[0011]FIG. 1 is a perspective view of a standpipe according to the present invention for an automatic transmission of a motor vehicle;

[0012]FIG. 2 is a partial cross-sectional view of a valve of the standpipe in a cold fluid position;

[0013]FIG. 3 is a partial cross-sectional view of the valve in a warm fluid position; and

[0014]FIG. 4 is a cross-sectional view of an alternative embodiment of the standpipe.

DETAILED DESCRIPTION OF THE PRESENTLY PREFERRED EMBODIMENTS

[0015]FIG. 1 shows one embodiment 10 of an apparatus according to the present invention for setting a level of fluid in an oil reservoir 12 of an automatic transmission of a motor vehicle. The apparatus 10 comprises a standpipe 14, a regulator 16, and a lever 18. The standpipe 14 includes a drain plug 20 that drains any excess fluid to a drain pan. The drain plug 20 is intact during normal operation.

[0016] The regulator 16 includes a generally vertical portion 22 and a horizontal portion 24 extending from the vertical portion. The vertical portion 22 is slidably disposed in an opening 26 in one wall of the standpipe. The horizontal portion 24 of the regulator is situated proximate the upper surface of the lever 18, which is pivotably mounted within the standpipe 14. A coil spring 28 is anchored to the standpipe 14, and includes a distal end 30 connected to the lever 18.

[0017] The coil spring 28 is thermally sensitive, i.e. its length varies as a function of the transmission fluid in which it is immersed. When the transmission is cold, the coil spring is relatively short, and the lever 18 assumes a first, generally horizontal position as shown in FIG. 2. As the temperature of the automatic transmission fluid rises, the length of the coil spring 28 increases to rotate the lever generally counterclockwise. During this process, the lever 18 biases the horizontal extension 24 of the regulator 16 upwardly to thereby raise the regulator in the opening 26 to a height shown in FIG. 3.

[0018] Any fluid above the level of the top of the regulator 16 drains into the interior of the standpipe 10 and out through the drain plug 20. When the transmission fluid is cold, the level at which this drainage occurs is relatively low. As the temperature of the fluid increases, this level also increases, preferably in a linear fashion. The height of the regulator 16 is calibrated to ensure that regardless of the temperature of the transmission, the fluid level can therefore be accurately set.

[0019]FIG. 4 shows an alternative embodiment 100 of the standpipe including a pipe 102 slidably disposed and suitably sealed in a thermal motor 104. A return spring 106 is situated between a reaction surface 108 of the thermal motor and a flange 110 proximate the bottom of the sliding pipe 102. The thermal motor 104 is filled with a fluid such as wax so that as the temperature of the transmission fluid increases, the volume of the fluid in the thermal motor expands, preferably at a linear rate. In the fashion described above with respect to the first embodiment of the invention, the height of the pipe 102 thereby varies with the temperature of the transmission fluid, and any excess fluid drains through a drainpipe portion 112 of the thermal motor. In operation the standpipe 100 includes a drain plug similar to the drain plug shown in FIG. 1.

[0020] The fluid level of the automatic transmission can thus be set accurately and as a function of the temperature of the fluid in the transmission or vehicle assembly plant, without the need for high cost tooling. In this environment, the top off process is performed by removing the center plug from the standpipe and introducing additional fluid to the transmission via a fill hole in the case. The regulator of the standpipe allows the excess fluid to flow into the center of the standpipe out of the transmission reservoir. Once the presence of fluid is detected, the fill equipment terminates the addition of fluid. The fluid level is thus precisely set for the given fluid temperature. The center plug and fill hole plug are installed and the process is complete. Additionally, setting the fluid level can be readily accomplished at either the service center or by the end user of the product using similar methods at the assembly plant.

[0021] The present invention thus allows the transmission oil level to be precisely set over a given operating temperature range, without the need for temperature measurement equipment or even a dipstick. While the embodiments of the invention disclosed herein are presently considered to be preferred, various changes and modifications can be made without departing from the spirit and scope of the invention. The scope of the invention is indicated in the appended claims, and all changes that come within the meaning and range of equivalents are intended to be embraced therein. 

1. An apparatus for setting a level of fluid in an oil reservoir of an automatic transmission, the apparatus comprising: a standpipe attached to the oil reservoir; a regulator movable relative to the standpipe; and means for moving the regulator relative to the standpipe to set a height of the regulator.
 2. The apparatus of claim 1 wherein the means for moving the regulator comprises a coil spring.
 3. The apparatus of claim 1 wherein the means for moving the regulator comprises a lever.
 4. The apparatus of claim 1 wherein the means for moving the regulator comprises a thermal motor.
 5. The apparatus of claim 1 wherein the means for moving the regulator is thermally sensitive.
 6. The apparatus of claim 1 wherein the height of the regulator is a function of temperature of the fluid.
 7. An apparatus for regulating a level of fluid in an oil reservoir of an automatic transmission, the apparatus comprising: a standpipe attached to the oil reservoir; a regulator movable relative to the standpipe; a lever mounted to the standpipe; and a coil spring engaged with the lever.
 8. The apparatus of claim 7 wherein the coil spring is thermally sensitive.
 9. The apparatus of claim 8 wherein a height of the regulator is a function of temperature of the fluid.
 10. The apparatus of claim 7 wherein the regulator is mounted as gate in the standpipe.
 11. The apparatus of claim 7 wherein the regulator is mounted as a sliding gate in the standpipe.
 12. An apparatus for regulating a level of fluid in an oil reservoir of an automatic transmission, the apparatus comprising: a standpipe attached to the oil reservoir; a regulator; and a thermal motor for moving the regulator relative to the regulator.
 13. The apparatus of claim 12 wherein the thermal motor is thermally sensitive.
 14. The apparatus of claim 12 wherein the thermal motor moves the regulator to a height as a function of temperature of the fluid. 